It is difficult to get a code reader that works on our old 2.5 Export CRDs as a PCI bus is used...newer KJs use a CAN bus.
Even the Local Bosch Service Center here in SA laughed at me when I asked if he could read my codes!
The "key" trick definitely works on the early KJs like ours...more on that later but it does not read air bag codes I believe.
The first thing to do before working on an air bag problem is to disconnect the red lead from the battery and turn this lead so that it touches the chassis....leave it like this for a few minutes so as to discharge any capacitance in the system so that the airbag does not get set off while you are working around there!
I had this problem with the air bag light on my 2002 2.5 Export CRD...at first intermittent and then pretty solid.
If you remove the plastic covers covering the steering column...needs a male Torx bit to remove two screws from underneath..you should see right near the bottom of the column a small harness of four or five wires connecting into the main harness via a small plastic plug. If you undo this connector...you will see that the plug that goes upwards towards the top of the steering wheel has a small flat metal section inside it which shorts out all the pins on that side of the connector as you pull the plug apart....this is done to short out the airbag actuators so as to stop any back EMF setting them off...this will show that you have located the correct plug!
Try re-plugging this plug a few times in case there is a bad connection and see if that fixes your problem. In my case the one set of pins refused to make a good contact for very long....I could reach down under the plastic covers and waggle this plug about and the air bag light would go ON/OFF. In the end I cut of the plugs and soldered the wires together and that finally fixed my problem. I believe only the RHD KJs have this short section of harness fitted!
If that does not fix your problem then you may need to replace the clock spring under the steering boss at the top of the steering wheel....I will post you a link to another site later where I typed out the whole procedure!
Then as far as using the "key" trick to get codes for your ABS issue....I do not believe the Key trick pulls out codes for the air bags so your air bag problem could be one of the other bags and not the Driver's bag!
Rapidly switch the ignition ON/OFF 4 times without starting the engine.
After the 4th ON action leave the ignition ON and the Odometer display should start displaying all the stored codes...the last code displayed is the latest code...write them down. This switching ON/OFF requires some practice to get the speed right but I use it fairly often.
The trouble with the Key method is:
Not all types of codes are displayed.
The codes are not erased by this process.
Some of the codes may be ancient and no longer of any value.
Sometimes the last two digits of the code are transposed so a P0152 code for instance may display as P0125 for example.
The codes are stored only once so for multiple re-occurances of a problem you still only get one code.
I deliberately caused a code on my CRD by pulling out one of the two Glow plug relays in the relay box under the bonnet (hood). The Jeep started OK although a bit roughly and posted a CEL. Now I use this code as my "marker" so that any code shown after my marker I know is a new code!
You can download the KJ Service Manual...includes the circuit diagrams here...the 2004 model is not included so the 2003 manuals have to used by 2004 owners!
The first thing to download though for Export CRD owners is the section called "2.4_2.8 Export Diesels" as it explains the early Export Diesel engines, gearboxes etc. better than the "2003 KJ Service Manual" does.
:
http://www.colorado4wheel.com/manuals/Jeep/KJ